Structural members such as beams must have the necessary strength to withstand the loads to which they will be subjected and must conform to a variety of other important parameters. Some of these parameters relate to safety in the event of a fire, the so called "fire rating" of the member. In this connection beams must be capable of sustaining a minimum rated load when subjected to specified high temperatures over a period of time so that the structure in which they are used will not become unstable too rapidly in the event of a fire.
Another consideration is the rigidity of the member which is particularly important in the case of beams since they tend to sag at the center. A beam which has excessive sag, camber or other deflection can be present serious construction problems even though it has sufficient strength because it will cause other members that it supports to be out of alignment and may, in extreme situations, cause these other members to fail. On the other hand, excessive rigidity may be undesirable, especially in earthquake prone areas.
At present, conventional construction techniques are becoming increasingly expensive, in large measure due to the cost of materials. One type of member for which costs have increased significantly is the so called "glue-lam" beam, which is of laminated wood construction and is commonly used in large non-residential structures such as supermarkets. The wood from which said beams are made, usually Douglass Fur, is available only in certain areas and transportation costs to other areas can be substantial. Moreover, the availability of glue-lam beams varies at different times and costly delays can result. It is also found that glue-lam beams are excessively heavy and their installation is, therefore, difficult.
Despite the need for inovation with respect to structural members, little use has been made of alternative materials such as fiberglass. This is partially due to the fact that fiberglass is extremely resilient and when used as a beam, for example, has unacceptable sag or camber despite the fact that it is other wise sufficiently strong. In addition, fiberglass typically is unable to retain its strength and integrity when subjected to high temperatures, even for short periods of time, and does not have an acceptable fire rating. State of the art fiberglass structural members are, therefore, in the majority of instances, incapable of meeting applicable building codes.
It is a principle objective of the present invention to provide an improved fiberglass structural member that overcomes the problems noted above. It is a further objective to provide such a member that has controllable resiliency.